Emergency abdominal radiology: the acute abdomen

35 Pages·2009·2.58 MB·English

RRAADDIIOOLLOOGGYY FFOORR PPRRAACCTTIITTIIOONNEERRSS
EMERGENCYABDOMINALRADIOLOGY: THE ACUTE ABDOMEN
http://www.lebanesemedicaljournal.org/articles/57-3/doc4.pdf
Ghina A. BIRJAWI1, Lara J. NASSAR1, Lamya A. ATWEH1, Samir AKEL2, Maurice C. HADDAD1
Birjawi GA, Nassar LJ, Atweh LA, Akel S, Haddad MC. associated symptoms such as fever, tachycardia, nausea
Emergency abdominal radiology: the acute abdomen. J Med and vomiting, hematuria, gastrointestinal bleeding, leuco-
Liban 2009 ; 57 (3) : 178-212. cytosis, hemodynamic status i.e. stable or unstable patient
in shock, and others that can help in short listing the diag-
nostic possibilities towards “ruling out” one or more acute
I. DEFINITION abdominal conditions. In terms of differential diagnosis of
acute abdominal emergencies, the authors of this article
The clinical entity of the acute abdomen, from a practi- adopted a simple classification based on the following ter-
cal standpoint view, describes a patient with acute minology: the “itis”i.e. inflammatory and infectious con-
abdominal pain of rapid or sudden onset, requiring sur- ditions such as appendicitis, diverticulitis, cholecystitis,
gical or immediate action [1]. It is assigned as prelimi- and many other diseases, the “tion”such as bowel perfo-
nary diagnosis until a specific diagnosis is established. ration, bowel, renal, biliary, and vascular obstruction, aor-
tic dissection, and intestinal or ovarian torsion, and the
II. CAUSES “nonspecific” abdominal pain. Aprovisional working or
presumptive diagnosis is made in approximately 50%
Based on studies of approximately 30,000 patients, de of cases, otherwise a clinical differential diagnosis is pro-
Dombal [2] noted that in one third of these cases, cause vided depending on history, physical examination, basic
was never established hence so-called unspecified abdom- blood tests including a full blood count and a serum crea-
inal pain. In those patients in whom a diagnosis became tinine level, urine analysis, and other laboratory tests of
evident, 28% had appendicitis, 9.7% acute cholocystitis, relevance. Requests for cross-sectional imaging namely
4.1% small bowel obstruction, 4% acute gynecologic dis- ultrasound and CTscan will follow if immediate surgery
ease, 2.9% acute pancreatitis, 2.9% renal colic, 2.5% per- is not indicated. Immediate surgery is indicated in patients
forated peptic ulcer, 1.5% cancer, and 1.5% diverticulitis. with a large pneumoperitoneum diagnosed on plain
Of course, several other causes not mentioned in this sec- abdominal radiographs (PAR), hemodynamically unstable
tion may be responsible for acute abdominal pain, some patient with spontaneous intraabdominal hemorrhage
of which will be discussed in this article. Grossly, acute detected on a bedside portable ultrasound examination.
abdominal conditions can be divided into traumatic and Selection of an appropriate imaging strategy is essential to
non traumatic conditions, in adults and elderly and in ensure prompt treatment.
pediatric patients with some inevitable overlap.
IV. CLINICALSCENARIOS AND IMAGING TECHNIQUES
III. CLINICALASSESSMENT
With regard to the selection of imaging strategies in the
The majority of patients with acute abdominal conditions emergency room, two clinical scenarios should be consid-
present to the Emergency Unit. It is of great importance ered at presentation. First, the patient presenting with
that the preliminary clinical assessment and the radiology abdominal pain and hemodynamically unstable condition
request form state the working presumptive/provisional with hypotension i.e. shock state. If the hematocrit level is
clinical or differential diagnosis, specify the rapid or low a hemorrhagic shock state should be suspected. For
insidious onset and the duration of the pain and whether this clinical scenario, a fast chest and abdominal sonogra-
the abdominal pain is diffuse or localized to a quadrant i.e. phy using hand held portable ultrasound equipment at the
to the epigastrium, right upper quadrant (RUQ), left upper bedside in the emergency room should be carried out in
quadrant (LUQ), right lower quadrant (RLQ), left lower 20 to 30 seconds looking for four major abnormalities:
quadrant (LLQ), or pelvic pain; and whether there are 1/Retroperitoneal hemorrhage from a leaking abdominal
aortic aneurysm (AAA) or ruptured angiomyolipoma of
From the Departments of Diagnostic Radiology1, Surgery2, the kidney or hemorrhagic pancreatitis. 2/ Presence of
American University of Beirut Medical Center, Beirut,
intraperitoneal hemorrhage or fluid from a ruptured vis-
Lebanon.
ceral aneurysm, liver tumor, ectopic pregnancy, or other
Correspondence: Ghina A. Birjawi, MD. American Uni-
conditions. 3/Hemopericardium or hemothorax from aor-
versity of Beirut Medical Center. Department of Diagnostic
tic dissection or rupture. 4/ Pyonephrosis from renal
Radiology. P.O. Box 11-0236. Beirut. Lebanon.
Tel: [phone] Fax: [phone] obstruction and urosepsis. Second, the patient presenting
e-mail: [email protected] with abdominal pain and hemodynamically stable con-
178 Lebanese Medical Journal 2009 • Volume 57 (3)
dition. In this clinical scenario imaging is important women where exposure to ionizing radiation is consid-
because the physical findings and laboratory studies are ered unacceptable, and in patients at higher risk for de-
often nonspecific, and abnormalities that may cause an veloping allergic and toxic reactions to iodinated contrast
acute abdomen are extraordinarily diverse and range media. Present data have not conclusively documented
from benign self-limited disorders such as gastroenteri- any deleterious effects of MR imaging on the developing
tis, mesenteric adenitis and others that may not require fetus. Therefore, no special consideration is recommend-
admission to hospital, to life-threatening illnesses such ed for the first, versus any other, trimester in pregnancy.
as bowel infarction or perforation, strangulated hernia, Pregnant patients can be accepted to undergo MR scans
necrotizing pancreatitis requiring immediate surgical at any stage of pregnancy. MR contrast agents should not
action i.e. a surgical emergency. Diagnostic imaging be routinely provided to pregnant patients [3]. However,
plays a pivotal role in triaging these patients rapidly, safe- low dose CTscan examination is increasingly used in the
ly, and decisively towards optimal therapy i.e. surgical United States for the primary diagnosis of acute abdomi-
versus nonsurgical. In this regard, several imaging tech- nal conditions in pregnant women and children. When
niques can be used that have practically replaced the performing an ultrasound examination of a patient with
physical examination starting with the simple conven- acute abdominal pain, it is essential that the operator ask
tional radiographs as the initial radiological investigation the patient to point out with one index finger the point of
i.e. “three-view acute abdominal series”consisting of a maximum tenderness, where the operator will apply the
combination of chest and abdominal radiographs in the transducer for an optimal examination.
erect and supine positions looking for intestinal obstruc- Avariety of CTtechniques that can be applied and tai-
tion or perforation with extraluminal air, radiopaque uri- lored to each clinical scenario are listed in Table I, to
nary calculi or appendicolith. The use of cross-sectional answer specific clinical questions. An algorithmic imag-
imaging techniques such as computed tomography (CT) ing approach to acute abdominal pain is suggested in
and color Doppler ultrasound (CDUS) has superseded at Table II.
large the conventional radiographs because of their high- Magnetic resonance and nuclear medicine imaging
er diagnostic accuracy. Because of major concern about studies have a limited selective role in the acutely ill-
exposure to high radiation doses and potential adverse patient. The use of MRI in the emergency setting is evolv-
allergic and toxic effects of intravenous contrast material ing [4]. Abdominopelvic MRI is often used in a problem-
administered to patients undergoing CT examinations, solving capacity as an adjunct second-line investigation
CDUS and magnetic resonance imaging (MRI) are non- in those patients with an unclear diagnosis on cross-
invasive imaging techniques that should be considered as sectional CDUS or CTimaging techniques, prior to lapa-
the modalities of first choice in children, and in pregnant roscopy.
TABLE I
VARYING AND TAILORED CTTECHNIQUES TO CLINICALSCENARIOS
NECT/Plain CT without IV or oral CM NECT & CECT + delayed images without oral CM
1.Renal or ureteric colic 1.Acute flank pain with normal kidneys on NECT➞CECT
2.Renal failure i.e. elevated serum creatinine level to R/O renal infarction or acute pyelonephritis
or equivocal renal or ureteric obstruction.
Biphasic CECTwith arterial and venous phases + oral water Monophasic CT angio with arterial phase only – without oral CM
1. Acute pancreatitis 1.Suspected acute abdominal spontaneous hemorrhage
2.Suspected leaking AAA
3.Polytrauma patient
4.Intrapelvic postpartum hemorrhage with uterine rupture
CECT – without oral CM CE/CTRC i.e. with rectal contrast
1.Suspected high grade SBO on PAR 1.Suspected acute appendicitis
2.Suspected acute mesenteric ischemia ➞Biphasic CTangio 2.Suspected colonic obstruction ➞Instant contrast enema
with arterial & venous phases
CECT + oral CM CECT with delayed urinary excretory phase
1.Diverticulitis 1.Suspected urine leakage after blunt trauma to the urinary tract
2.PEA or post surgical injury to the urinary tract with urinary ascites
3.Low grade/intermittent/partial or incomplete SBO or urinoma formation
4.Small pneumoperitoneum
NECT : non enhanced CT IV : intravenous ; CM: contrast media CECT : contrast enhanced CT
R/O : rule out AAA: abdominal aortic aneurysm SBO : small bowel obstruction
PAR : plain abdominal radiographs CE/CTRC : contrast enhanced CTwith rectal contrast PEA: primary epiploic appendagitis
G. A. BIRJAWI et al. – Emergency Abdominal Radiology Lebanese Medical Journal 2009 • Volume 57 (3) 179
TABLEII
SUGGESTED ALGORITHMIC IMAGING APPROACH FOR THE DIAGNOSTIC WORKUPOF ACUTE ABDOMINALPAIN
+
CDUS: color Doppler ultrasound PAR: plain abdominal radiographs NECT: non-enhanced CTscan RUQ: right upper quadrant
LUQ : left upper quadrant LLQ : left lower quadrant RLQ : right lower quadrant
CE-CT + OC: contrast enhanced CTscan with oral contrast CE-CTRC : contrast enhanced CTscan with rectal contrast
180 Lebanese Medical Journal 2009 • Volume 57 (3) G. A. BIRJAWI et al. – Emergency Abdominal Radiology
Hepatobiliary scintigraphy [5] is indicated in patients a total body MDCTangiography is performed even if
with suspected acute cholecystitis and equivocal CDUS the patient is hypotensive and hemodynamically un-
or CT findings, and in patients with suspected bile leak stable, looking for surgically treatable conditions that
or biloma formation from bile ducts injury following can be treated by interventional radiologists such as
abdominal trauma or iatrogenic injury. active arterial bleeding with extravasation of the con-
Invasive angiographic and interventional transcatheter trast medium i.e. contrast blush detected on MDCT
procedures performed percutaneously by interventional images, treatable by immediate transcatheter emboliza-
radiologists under imaging guidance play an important tion at admission. Lack of renal enhancement indicates
role in the management of acute abdominal conditions in renal artery injury treatable with stenting within the first
some selected cases with appropriate indications. 6 hours following trauma. If the patient is unconscious
a nonenhanced head CTscan should be also performed.
V. DIAGNOSTIC IMAGING & PATHOLOGYIN ADULTS 2. In non specialized trauma centers, as in the case of
practically all emergency centers in Lebanon includ-
For all practical purposes, the authors based on personal ing our emergency unit, the scenario is different. If the
experiences and review of the literature, have preferably patient is hymodynamically unstable i.e. with a blood
adopted the classification of traumatic versus non trau- pressure < 80 mmHg the patient should not be moved
matic abdominal conditions, an imaging approach based from the RR, and a “focused assessment sonography
on the localization of pain to an abdominal quadrant, fortrauma (FAST)” is performed using a hand held
taking also in consideration the age of the patient. Abrief portable ultrasound machine at the bed-side looking
discussion of the common causes of acute abdominal for a hemopericardium, hemothorax, or a hemoperi-
emergencies with the appropriate and up-to-date usage of toneum [9], together with portable chest and pelvis
imaging diagnostic strategies and techniques with illus- radiographs and lateral projection of the cervical spine
trative examples is presented. to exclude an unstable cervical spine fracture, prior
to surgery. If the patient is hemodynamically stable
A. ABDOMINALTRAUMA i.e. blood pressure > 80 mmHg or marginally stable
BP = 80 mmHg, he can be moved to the Radiology
Abdominal trauma will be discussed here in the context Department for investigation. Ahelical CT angiogra-
of polytraumatized patients, because abdominal trauma is phy (with delayed image acquisition at 10 minutes if
often associated with trauma to other parts of the body, there is suspicion of upper urinary tract injury to the
especially in severely injured patients involved in road pelvicalyceal system with urine extravasation, or with
traffic accidents or fall from a height. Few important a conventional retrograde urethro-cystography if there
points should be addressed regarding the management exists suspicion of lower urinary tract injury) is usual-
of a polytraumatized patient i.e. transport, resuscitation, ly performed looking for ongoing active arterial hem-
investigation, and treatment action or therapeutic options orrhage with extravasation of contrast medium that
of a critically injured individual [6-8]. can be treated by transcatheter embolization at the
First, “time is life”i.e. a quick transport from the field angiography suite (Fig. 1a). With regard to trans-
of injury to the emergency room is of crucial importance. catheter therapy the aim is to achieve hemostasis by
Ambulances for short distances and helicopters for long either embolization or balloon vessel occlusion prior
distances play an important role in patient’s survival by
applying the “load and go” principle, of course after
adequate immobilization of the victim of injury on a
brancard and applying “first aid” resuscitation.
Second, upon arrival to the emergency room (ER) the
principle of the “Golden Hour”should be applied i.e. in
the first 30 minutes the patient is resuscitated and hemo-
dynamically stabilized in the resuscitation room (RR) and
his conscious status assessed, and in the second 30 min the
patient should be investigated for a diagnosis and imme-
diately treated. In the second 30 min of the “Golden Hour”
principle, two different scenarios can be observed depend-
ing on availability of local facilities and expertise:
1. In advanced “Specialized Trauma Centers” in Europe
& the United States where an integrated multidetec-
tor CT (MDCT) and angiography units are available
FIGURE1a
on-site in the ER with dedicated trauma and interven-
Contrast enhanced helical CTangiography showing
tional radiologists staff on-duty available 24 hours, no
extravasation of contrast material (arrow) (131 HU)
mobilization of the patient or the resuscitation team or compatible with active bleeding secondary to
ancillary equipment is required. In a conscious patient a pelvic fracture.
G. A. BIRJAWI et al. – Emergency Abdominal Radiology Lebanese Medical Journal 2009 • Volume 57 (3) 181
became crucial members of the fist-line team of doctors
in the management of MCI’s. Fast imaging plays an
important role in the secondary triage process of criti-
cally injured individuals who need further management
and hospitalization, thus improving mortality or death-
to-injury rates. Adisaster plan with emergency radiolo-
gy preparedness and a bomb threat plan with regular
drill tests should be developed as part of every hospi-
tal’s policies and procedures [10].
B. NONTRAUMATIC CONDITIONS
1. Acute Right UpperQuadrant (RUQ) Pain
a. Acute cholecystitis•In the right upper quadrant, acute
cholecystitis and biliary colic or acute cholangitis are by
far the most common diseases, other less important and
frequent diseases that cause RUQ pain include: liver
abscess and spontaneous rupture of a hepatic neoplasm.
CDUS is the preferred imaging method for evaluating
patients with acute RUQ pain. It is a reliable technique
for establishing the diagnosis of acute cholecystitis with
a high accuracy of 92% [11]. The imaging findings con-
sist of primary signs or major criteria for diagnosis such
as detection or visualization of gallstones obstructing
the gallbladder neck or cystic duct, a positive Murphy’s
sonographic sign, and minor criteria or secondary diag-
nostic signs such as gallbladder wall thickening of
3 mm or greater, overdistension of the gallbladder with
a largest diameter of 4 cm or greater, and evidence of
pericholecystic fluid or biliary sludge (Fig. 2). In pa-
FIGURE1b. Selective transcatheter coil embolization of tients with suspected emphysematous cholecystitis i.e.
the bleeding vessel shown in 1a, a branch of the left internal diabetic, HIV and immunosuppressed individuals, a
iliac artery, was successfully performed achieving hemostasis. plain abdominal radiograph or better a nonenhanced CT
scan may supplement the CDUS in order to confirm
to definitive surgery (Fig. 1b). Asuperselective distal or the diagnosis of emphysematous cholecystitis. In pa-
peripheral embolization using microcoils through a tients with suspected gangrenous cholecystitis, the pain
coaxial system i.e. an outer 5F catheter or 6F guiding is usually absent with a negative Murphy’s sonographic
catheter with an inner 3F microcatheter, is usually re-
quired and preferable. However, emergency hemostatic
selective embolization with a 4F or 5F catheter is also
desirable, performed as a life-saving procedure by gen-
eral radiologists. Embolization should be performed
quickly and as soon as possible for hemorrhage control
i.e. hemostasis for two reasons: first, patients receiving
multiple or massive blood transfusions usually develop
wash-out coagulopathy, in this instance it may become
difficult to stop bleeding or achieve hemostasis with
distal embolization and microcoils therefore a more
proximal embolization of the main feeding trunk with
compact coils may be necessary; second, in patients
with hypovolemic state and pre-shock vasoconstriction
or vasospasm occurs, it prevents distal catheterization
for embolization.
Aspecial circumstance may occur with terror attacks
consisting of suicide bombers and massive explosions,
resulting in a large number of injured individuals arriv- FIGURE2.. Sonography showing an impacted large 2.4 cm
ing to Emergency Unit in a very short period of time, stone in the gallbladder neck, gallbladder distension and
so-called mass casualty incidents (MCI’s). Radiologists biliary sludge in a patient with acute cholecystitis.
182Lebanese Medical Journal 2009 • Volume 57 (3) G. A. BIRJAWI et al. – Emergency Abdominal Radiology
sign, color Doppler flow imaging or contrast enhanced tis which enters in the differential diagnosis. Magnetic
CTscan show absence of vascularity or enhancement resonance cholangiopancreatography (MRCP) is a
in the gallbladder wall and sloughing of the mucosa. totally noninvasive imaging technique capable of
CT and Tc-HIDA hepatobiliary scintigraphy may be detecting choledocholithiasis in patients with no biliary
helpful as second-line investigations for confirmation sepsis with a high sensitivity approaching 96% [15].
of the diagnosis if the sonographic diagnosis of acute However, it is not widely used because of some tech-
cholecystitis is equivocal. nical limitations: a minimal cooperation from the
Acute acalculous cholecystitis (AAC) occurs in patient remains necessary to obtain optimal quality
patients who are critically ill in intensive care units. It images, low availability of MR imaging especially
is thought to be secondary to a functional obstruction with non scheduled appointments for emergency
of the cystic duct. The sonographic findings may be patients with biliary sepsis, some pitfalls in image
nonspecific, therefore the sonographic diagnosis of interpretation i.e. stones smaller than 5 to 6 mm may be
AAC can be difficult. Diagnostic percutaneous needle overlooked, and a final major limitation of MRCP
aspiration of bile from the gallbladder for Gram stain which represents only a diagnostic and not a therapeu-
and culture, and a percutaneous transhepatic cholecys- tic procedure. This is why endoscopic ultrasound
tostomy performed at the bedside under sonographic (EUS) and endoscopic retrograde cholangiopancrea-
guidance are valuable methods for confirming the tography (ERCP) have gained wide acceptance and
diagnosis of AAC and relieving obstructive and in- became the procedure of choice for diagnosis and treat-
flammatory changes. ment of choledocholithiasis, as an emergency proce-
b. Biliary colic and acute cholangitis•Choledocholithia- dure especially in patients with biliary obstruction and
sis is seen at the time of cholecystectomy in 8% to sepsis requiring emergency drainage by sphincteroto-
15% of patients younger than 60 years old, and 15% my and balloon or Dormia basket extraction of stones,
to 60% of patients older than 60 years of age [12]. with a success rate of 87% [16]. If the stones cannot be
Patients with or without cholecystectomy presenting removed, a nasobiliary tube or preferably an internal
with common bile duct stones, may have a biliary colic stent may be left in place for drainage. In a few
with or without cholangitis, pancreatitis, jaundice, and instances, when endoscopy is not feasible especially
abnormal liver function tests (LFT’s) especially an ele- in patients with previous surgery and biliary-enteric
vated serum alkaline phosphatase level due to biliary anastomosis, percutaneous transhepatic management is
obstruction. useful. In critically-ill or high-risk elderly patients with
Diagnosis of choledocholithiasis may be difficult multiple medical problems, presenting with cholangitis
especially with sonography because more than one secondary to biliary obstruction and sepsis, and con-
third of patients with choledocholithiasis have no sidered at risk i.e. not candidates for surgery, ERCP, or
biliary ductal dilatation that usually makes detection of percutaneous transhepatic cholangiography (PTC), a
bile duct stones much easier (Fig. 3). The overall percutaneous cholecystostomy (Fig. 4) under CTguid-
reported sensitivity of sonography for detection of ance or at bedside under ultrasound guidance can be
choledocholithiasis is low estimated at 70% (range 22- performed. This is usually performed as a simple first
85%) [13-14]. The main application for sonography in stage procedure and temporizing measure to relieve
patients with suspected biliary sepsis, jaundice, and obstruction and culture the aspirated bile specimen,
abnormal LFT’s is the detection of bile duct dilatation prior to a definitive second stage procedure consisting
and differentiation of obstructive jaundice from hepati- of balloon dilatation of the sphincter of Oddi and
FIGURE3
Dilated common
bile duct measuring
1.3 cm in diameter
containing
a large 1.2 cm stone
(arrow) on sonography.
FIGURE4
Cholecystostomy tubogram showing complete
obstruction of the common bile duct by a stone (arrow).
G. A. BIRJAWI et al. – Emergency Abdominal Radiology Lebanese Medical Journal 2009 • Volume 57 (3) 183
biliary stenting of the common bile duct over a guide alternative diagnoses or mimickers of AAin 32% of
wire manipulated across the cystic duct. patients investigated with helical CTRC to rule out
AAin whom a normal appendix is identifiable [19].
2. Acute Right LowerQuadrant (RLQ) Pain On helical CTRC, a thickened appendix, with non-
a. Acute appendicitis (AA) • It is the most frequent opacification of its lumen with contrast material,
cause of acute RLQ pain. Other less common causes enhancement of its wall and periappendiceal fat
include: mensenteric adenitis, primary epiploic streaking, are diagnostic signs of noncomplicated AA
appendagitis, caecal diverticulitis, right lower lobe (Fig. 5), even a tip appendicitis can be easily diag-
pneumonia with referred pain to the RLQ, infectious nosed with CTRC. In complicated AAby rupture or
and inflammatory enterocolitides, torsion of Meckel’s perforation, free fluid in the abdomen and pelvis,
diverticulum, and neutropenic typhlitis in immuno- periappendiceal abscess formation, ureteric or intesti-
suppressed and cancer patients. Classically, the diag- nal obstruction may be observed. In the recent litera-
nosis of AA is primarily a clinical diagnosis in ture, there is an emerging consensus for routine use of
approximately 70 to 78% of patients with typical clin- CT for most if not all adult patients with suspected
ical and laboratory findings, they undergo surgery AA.
without preoperative imaging. In about 20% of clini- b. Ureteric colic • Ureteric colic caused by acute right
cally equivocal patients with atypical findings or clin- ureteric calculus obstruction may cause RLQ pain
ical presentation, the clinical diagnosis of AA may radiating to the flank, or inguinal region and scrotum.
be uncertain, therefore appendiceal cross-sectional Similarly, an acute left ureteric calculus obstruction
imaging is required to confirm or exclude the diagno- may cause left lower quadrant pain. For several years
sis of AA[17]. intravenous urography has been the primary corner-
Plain abdominal radiograph has a limited diagnos- stone investigation used in patients with suspected
tic value in the diagnosis of AA; it may show an urolithiasis induced urinary colic. Nowadays, nonen-
appendicolith which is only present in 15% of hanced CTscan of the abdomen and pelvis (Fig. 6) is
patients with AA. It is important to mention that universally considered including at our institution
appendicoliths can also be seen in the absence of [20-21] as the imaging modality of first choice for
appendicitis. The most widely used imaging tech- patients suspected with urinary calculus obstruction.
niques for diagnosis of AA are graded compression Virtually all ureteral calculi are radiopaque and dense
ultrasound (US) using a high frequency 5-12 MHz on CT, regardless of their chemical composition. Uric
linear probe and CTscan. US has become an impor-
tant imaging option in the evaluation of AA, particu-
larly in children and pregnant women because of radi-
ation concern. If the results of US are equivocal or
indeterminate, further evaluation by MRI or contrast
enhanced low dose CT with intravenous and rectal
contrast may be required in a small minority of
patients. On sonography, the identification of a
swollen and thickened, noncompressible appendix
greater than 6 mm in diameter is diagnostic of AA.
Because of its exceptional accuracy CT scan has
emerged in many centers including our institution
as the primary imaging modality for patients with
suspected AA especially those presenting outside
working hours and examined by junior housestaff. At
our institution, multislice helical CTscan with intra-
venous and rectal contrast administration (CTRC)
proved to be a highly useful and effective technique
allowing a quick and accurate diagnosis for appropri-
ate management of AA and avoiding unnecessary
surgery for nonsurgical conditions. The use of helical
CTRC with its high accuracy of 94.7% in the diagno-
sis of AA [18], has resulted since its introduction
in the year 2002 in a significant reduction of negative
appendectomy rate to 4% as compared to a previous
negative appendectomy rate of 16% prior to the year
2002 according to a study of Performance Indicator FIGURE5. Contrast enhanced CTscan with rectal contrast
(PI) conducted in our hospital (Dr. Ayman Tawil, per- showing an inflamed thickened nonopacified appendix
sonal communication), and allowed identification of compatible with a noncomplicated acute appendicitis (arrow).
184 Lebanese Medical Journal 2009 • Volume 57 (3) G. A. BIRJAWI et al. – Emergency Abdominal Radiology
b
FIGURE6.
a.Nonenhanced CTscan showing an enlarged right kidney with
mild hydronephrosis and perinephric fat streaking due to
a
obstruction by a 4 mm ureteric stone in b.
acid stones have attenuation values of 300-500 HU, usually diagnostic. If the combination of PAR and
and calcium-based calculi have attenuation values CDUS is negative i.e. no dilatation of the upper renal
higher than 1000 HU [22]. When no ureteric calculus tract exists and the calculus not visualized by PAR, a
is detected, a search for an alternative diagnosis should limited single-shot urography intravenous film taken
be instituted. Noncalculous urinary tract abnormalities 10-15 minutes after injection of contrast is still a good
causing symptoms of renal colic or acute flank pain examination for confirmation or exclusion of the diag-
with or without microscopic hematuria include acute nosis in children [24]. Gadolinium enhanced MR
pyelonephritis and renal infarction. In this clinical urography will achieve the same result, however non-
context, a repeat of CTexamination with intravenous enhanced low dose CTscan examination (80-100 mA,
contrast material administration is required to estab- at 120-140 kV) is increasingly used in the United
lish a diagnosis. Also, in approximately 3% of cases States for the primary diagnosis of ureteric calculous
differentiation of a ureteric calculus versus a calcified obstruction in pregnant women and children [25], and
phlebolith in the pelvis may be difficult on nonen- even in adults with a reduction in effective radiation
hanced CT scan, therefore a repeat CT examination dose by 38-56% [26].
with intravenous contrast material and delayed imag-
ing at excretory phase is necessary to ascertain a diag- 3. Acute Left UpperQuadrant (LUQ) Pain
nosis of ureteric calculous obstruction. In pregnant Acute abdomen with LUQ pain is not frequent. Splenic
women with suspected ureteric colic, CDUS can be infarction (Fig. 7) or abscess, gastritis or gastric ulcer
helpful for the diagnosis of acute ureteric calculous and irritable colon or constipation are the most important
obstruction [23]. In children with suspected ureteral causes of acute LUQ pain. The diagnosis of gastric or
calculous obstruction, PAR coupled with CDUS are colonic pathology is established by endoscopy, with
imaging playing a minor role. However, CT enables
accurate evaluation of splenic pathology.
4. Acute Left LowerQuadrant (LLQ) Pain
a. Diverticulitis • In the LLQ, diverticular disease is
the most common cause of acute abdominal pain.
Diverticulitis occurs in up to 25% of patients with
known colonic diverticulosis. It can also affect the
caecum causing caecal diverticulitis with RLQ pain
simulating AAor a colonic malignancy especially in
elderly people, the clue to the diagnosis is clinical
with identification of diverticulae in other segments
of the large bowel on CT scan. Contrast enhanced
CTwith intravenous and oral contrast material reach-
ing the large bowel is very sensitive and approaches
100% specificity and accuracy in the diagnosis or
exclusion of diverticulitis [27-28].
Figure 7 The CT diagnosis of diverticulitis relies on the
Contrast enhanced CTscan showing a large wedge shape identification of colonic diverticulae, segmental
splenic infarct. colonic wall thickening, and pericolonic mesenteric
G. A. BIRJAWI et al. – Emergency Abdominal Radiology Lebanese Medical Journal 2009 • Volume 57 (3) 185
inflammatory changes (Fig. 8). Occasionally, patients
with diverticulitis may present with a pericolic abscess
that can be drained percutaneously by a draining
catheter under CTguidance, as a temporizing measure
prior to elective surgery as a definitive treatment
(Fig. 9). The use of contrast enhanced CT scan with
rectal contrast in patients with suspected diverticulitis
is to be avoided because of the risk of perforation and
inducing blood septicemia. However, we have observ-
ed cases of caecal diverticulitis diagnosed by contrast
enhanced CTwith rectal contrast in patients presenting
with RLQ pain in the emergency setting without any
complications (Fig. 10).
b. Primary epiploic appendagitis (PEA) • Contrast
enhanced CTwith intravenous and oral contrast medi-
um is very useful for detecting other causes of LLQ
Figure 8. Contrast enhanced CTscan with oral contrast
pain such as PEAwhich is a nonsurgical self-limiting
reaching the large bowel, showing diverticulitis of
condition managed with conservative treatment [29].
the descending colon (arrow).
PEA is caused by torsion of the epiploic appendage
with resultant ischemia and fat necrosis. CT shows a
pericolonic fat attenuating mass located adjacent to
the anterolateral serosal surface of the colon (Fig. 11).
PEAcan affect any segment of the colon including the
ascending and transverse colon causing localized pain.
5. Acute Epigastric, Central and Diffuse Abdominal Pain
Any disorder that irritates a large portion of the gastro-
intestinal tract and/or the peritoneum causes diffuse
abdominal pain. The most common disorders are infec-
tious gastroenterocolitis, acute pancreatitis, acute mesen-
teric ischemia, bowel obstruction and pseudoobstruction,
a gastrointestinal tract perforation, leaking abdominal aortic
aneurysm, spontaneous intraperitonal hemorrhage, and
others.
a. Acute pancreatitis • An important cause of epigastric
pain is acute pancreatitis. Ultrasound (US) is helpful
for the demonstration of gallstones as a cause of gall-
stone pancreatitis and for follow-up of known peripan-
creatic fluid collections occurring in patients with pan-
creatitis. US is not helpful for the radiologic diagnosis
of acute pancreatitis. In patients with elevated serum
amylase and lipase levels suspected to have acute pan-
creatitis, contrast enhanced CT scan with oral water
administration (Fig. 12) is the modality of choice for
early diagnosis of acute pancreatitis and assessment of
the severity of acute pancreatitis using a CT severity
index developed by Balthazar et al. [30-31] to stage the
extent of the disease, and for detection of complica-
tions that may develop in patients with pancreatitis
such as pancreatic tissue necrosis and peripancreatic
fluid collections, splenic or portal vein thrombosis and
b
splenic artery pseudoaneurysm. Surgical debridement
FIGURE9 i.e. necrosectomy is the treatment of choice of necro-
a.Contrast enhanced CTscan with oral contrast showing
tizing pancreatitis associated with greater than one
a pericolonic abscess (arrow) due to sigmoid diverticulitis.
third of pancreatic tissue necrosis. However, the percu-
b.Percutaneous catheter drainage of the pericolonic abscess
taneous catheter drainage of peripancreatic fluid col-
was performed. Tubogram showing opacification of
the large bowel secondary to a communication between lections may be attempted to alleviate infection as a
the pericolonic diverticular abscess and the large bowel. temporizing measure to improve a critically ill high-
186 Lebanese Medical Journal 2009 • Volume 57 (3) G. A. BIRJAWI et al. – Emergency Abdominal Radiology
a
FIGURE10 b
a.Contrast enhanced CTscan with rectal contrast showing
ascending colon and caecal diverticulitis in an adult patient with right lower quadrant pain clinically suspected to have acute
appendicitis.
b.Alower CTsection showing caecal diverticulitis, a normal appendix opacified with contrast (straight arrow), and a diverticulum
of the sigmoid colon (curved arrow).
a
b
FIGURE11
a.Contrast enhanced CTscan with oral contrast of a patient presenting with left lower quadrant pain, showing absence
of diverticular disease but the presence of fat streaking and thickening anterior and adjacent to the descending colon (arrow)
compatible with primary epiploic appendagitis.
b.Follow-up CTscan after conservative management, showing complete healing of the pericolonic inflammatory changes.
risk operative patient prior to definitive surgical de-
bridement. In patients with acute pancreatitis and no
pancreatic tissue necrosis or with less than one third of
pancreatic tissue necrosis, antibiotherapy coupled with
percutaneous catheter drainage using multiple large
bore 14F catheters is a viable therapeutic option with a
success rate ranging from 50% to 80%; however, if no
improvement or any deterioration in the clinical course
are observed, then surgery becomes mandatory.
b. Acute mesenteric ischemia•Two important causes are
responsible for acute mesenteric ischemia: 1/ Occlusive
diseases i.e. embolic in cardiac patients with atrial fib-
rillation or left ventricular aneurysm and a mural throm-
bus, thrombosis of mesenteric artery or vein in patients
with hypercoagulable states, and dissection; 2/ Non-
FIGURE12. Contrast enhanced CTscan with water oral
occlusive diseases i.e. due to hypoperfusion in the intake showing acute pancreatitis with pancreatic necrosis
mesenteric territories from low flow states in elderly of the tail of the pancreas demonstrating lack of pancreatic
cardiac patients with decompensated congestive heart tissue enhancement with contrast material.
G. A. BIRJAWI et al. – Emergency Abdominal Radiology Lebanese Medical Journal 2009 • Volume 57 (3) 187